Poly-2-alkyl-2-oxazolines (I) are known compounds and are readily prepared by the ring opening polymerization of substituted oxazolines (II). ##STR1## The substituents are hereinafter defined. This polymerization is typically conducted in the presence of a cationic polymerization catalyst at a reaction temperature of about 0.degree.-200.degree. C. Typical catalysts include strong mineral acids, organic sulfonic acids and their esters, acidic salts such as ammonium sulfate, Lewis acids such as aluminum trichloride, stannous tetrachloride, boron trifluoride, and organic diazonium fluoroborates, dialkyl sulfates, and other such known catalysts. The reaction is further described by Tomalia et al., J. Polymer Science 4, 2253 (1966); Bassini et al., Polymer Letters 5, 871 (1967); and Seeliger, German Pat. No. 1,206,585. Jones et al., U.S. Pat. No. 3,640,909 teach the use of poly-2-alkyl-2-oxazolines as flocculants and as additives in the manufacture of paper.
Known acid-dye receptors for regenerated, cellulosics include polyvinylpyrrolidone, tertiary amines, and quaternary ammonium salts. However, such compounds are chemically and structurally dissimilar to the poly-2-alkyl-2-oxazolines here used.